A layout event involving old parent reference.
Used to related "move" and "delete" node events.
author: Peter Kharchenko pkharchenko@interactivebusiness.com" version: 1.0
Construct a LayoutMoveEvent from a given source,
node, and node's old parent.
Parameters: source - an Object that generated the event Parameters: node - an UserLayoutNodeDescription of the node that was involved Parameters: oldParentNodeId - a String value of an old parent id